Grading systems in head and neck dysplasia: their prognostic value, weaknesses and utility

Head & Neck Oncology

Table 2 Observer variability in head and neck lesions.

Studies/References	Localisation	Number of slides	Histopathological classification	Number of examinators	Agreement	Kappa value
Abbey et al. 1995	oral cavity/oropharynx	120	WHO°	6	35.8–57.5%	0.15–0.41
Fischer et al. 2004¹	oral cavity/oropharynx	87	WHO°	24		0.59 (95% CI: 0.45–0.72) 0.70 (95% CI: 0.56–0.84)²
Karabulut et al. 1995	oral cavity/oropharynx	100	WHO°	4	49–69%	27–45%³
Tabor et al. 2003	oral cavity/oropharynx	43	WHO	3	53%	0.58
Abbey et al. 1998	oral cavity/oropharynx	120	WHO°	6	38.5%	0.17⁴
Brothwell et al. 2003	oral cavity/oropharynx	64	WHO°	3	51%	0.37
Kujan et al. 2006¹	oral cavity/oropharynx	68	WHO and binary system ("low-risk" or "high-risk")	4	WHO: 37.7% (unweighted) 92.8% (weighted) Binary system: 74.3%	WHO: 0.22 (95% CI: 0.11–0.35 unweighted) 0.63 (95% CI: 0.42–0.78 weighted) Binary system: 0.50
Mclaren et al. 2000	larynx	100	WHO and two-grade (low and high grade)	13		WHO: 0.32 Two-grade: 0.52

° = WHO is not explicitely stated, but terms are in agreement with this system.
¹ = The unweighted kappa considers all disagreements to be equally important, while the weighted kappa (Kw) yields a higher reliability when disagreements between raters are small compared with when they are large.
² = the pathologic diagnoses are restricted to three categories ('no abnormality/hyperkeratosis', 'mild, moderate, or severe dysplasia', 'carcinoma in situ/carcinoma').
³ = when comparing the kappa values between the two pairs of pathologists with the same education, these values did not diverge from the general level of kappa values, indicating that the interobserver variability was due to individual differences rather than to educational background.
⁴ = Clinical information submitted with biopsy. Same population as [37].